The present invention relates to a device for rolling up a paper web and ejecting the formed roll. More particularly, the present invention relates to a device intended for rolling up image-bearing sheets which have just been produced by copying or printing, e.g. constructional or building drawings, which are of relatively considerable length, of more than about 0.5 meter. The device of the present invention is disposed on the outlet side of a suitable (re)production machine in order to receive the sheet in web form, roll it up, frequently without a core and possibly provide it with an anti-unroll means, and eject it into a receiving tray.
A roll-up device known from U.S. Pat. No. 5,466,328 comprises a sheet feed with a top guide and a bottom guide and two drive rollers which form a nip, the sheet feed emerging into a roll-forming space defined by three arcuate guides, one of which forms the continuation of the top guide. Three roller assemblies are also provided at the periphery of the roll-forming space, two at the bottom and one at the top, and they extend inwardly between the arcuate guides and are driven in order in turn to move a fed sheet around in the roll-forming space. When the sheet has been completely rolled up, the bottom two drive roller assemblies with the guide extending between them are swung away so that the roll-forming space forms an ejection opening at the bottom, from which the roll can drop down into a receiving tray. For the pivoting of the bottom drive roller assemblies, and hence also at least a part of the drive mechanism for these rollers, a relatively complex and space-occupying construction is required, which can result in malfunctioning of the roll-up device. During the forming of the roll, the diameter of the roll-forming space in the known roll-up device is determined by the gripper surfaces of the drive roller assemblies, which are disposed at fixed points during the roll-up process. This results in constraints on the dimensions of the sheet rolls which can be made with this device.
A simpler roll-up device is known from German Patent Application 43 38 146. This roll-up device comprises a roll-forming space defined by two drive roller assemblies situated diametrically above and opposite one another and two arcuate guides which are also disposed diametrically opposite one another and which extend substantially along the periphery between the drive rollers. One arcuate guide and the bottom drive roller assembly are disposed at fixed points. The other, top drive roller assembly is so mounted in the frame that it can move in a radially outward and upward direction. The other, pivotable guide can also be pivoted away for this purpose after the first coil of the roll has been completed. As a result, during formation, the roll has the opportunity of increasing in size while the sheet drive and guidance continue. After the roll is complete, an adhesive strip is fed over the fixed roller assembly in order to close the formed roll, and with the guide completely swung away an ejection opening is freed for the roll. By only driving the bottom roller assembly at the fixed point, the roll is forced out of the roll-forming space and can drop into a receiving tray. With this roll-up device as well, additional steps are required to make a drive roller assembly movable.
U.S. Pat. No. 5,011,093 discloses a roll-up device in which the roll-forming space is bounded at the top by a fixed arcuate guide provided with a number of freely rotating rollers for reducing the friction. At the bottom, the roll-forming space is defined by a comparable arcuate guide which, however, is pivotable so that it can be swung away after the rolling process in order to free an ejection opening for the roll. Also, this bottom guide is so suspended from the top guide that it can yield, to a limited degree, against the spring force to follow an increase in the size of the roll during formation. At one end the bottom guide is also provided with a drive roller driven by a freely rotating roller disposed in the sheet feed path and itself driven by a driven roller with which this roller forms a nip. One disadvantage of this roll-up device is that when the bottom guide yields during the formation of the roll, the degree of engagement between the drive roller and the freely rotating roll is changed. Steps must also be taken to enable the drive roller to be moved away from the freely rotating roll during the pivoting away of the bottom guide. As a result of the reduced degree to which the bottom guide can yield, the lengths of sheets for rolling are also limited, with lengths of 1.5 to 3 meters being referred to.
There is a need for a simple roll-up device capable of reliably rolling up a wide variety of relatively considerable lengths (e.g. from 0.5 to 10 meters) of image-bearing sheets, such as copy sheets and drawings. The sheet should be permanently driven at the roll periphery during the rolling-up process and the roll should have space to increase in size.